Wood-screw



U. MILLER. WOOD SCREW N Z6,509. Pat ent edDec. 20, 18,59.

J42 vemgmfjywnew I My UNITED STATES CHARLES MILLAR, or UTIQA, NEW romp woon-sonnw.

Specification of Letters Patent No.

To all whom it may concern:

Be it known that I, CHARLES MILLAR, of the city of Utica, in the county of Oneida and State of New York, have invented a new and useful Improvement in Wood- Screws; and I dohereby declare that the following is a full and exact description thereof, reference being had. to the accompanying drawing and to the, letters of refabove the thread, will follow the hole made by the stem or base of the screw without objectionable friction.

In the construction of wood screws, the thread is formed by turning out the intermediate spaces between its convolutions and leaving the diameter of the threadedpartmeasuring from outside to outside of the thread,and that of the shank, which lies between the threaded part and thehead-of equal diameter. In driving such a screw the thread makes a spiral trench or incision beyond the circumference of the stem; but the clearperforation left for the entrance of the shank is only of the size of the stem or cylindrical base of the thread. When the shank of such a screw reaches the wood in driving and care is nottaken to enlarge the orifice for its entrance there is more or less difliculty in forcing it down; and the great friction occasioned by the process draws severely upon the fibers of the wood which lie between the coils of the screw thread, thereby greatly weakening the hold of the screw. To guard against this friction, a larger gimlet is sometimes used to enlarge the outer part of the orifice. But in the use of the gimlet pointed screw where many of the smaller sizes are driven in soft wood without the use of either gimlet, or brad awl, this enlargement cannot always be 26,509, dated ne -e e 2o, 1s59.- I

made; and thescrew fiisinecessarily forced down, against all: obstructions. {My inven "5 tion entirely obviates; alljthese difliculties I turn off the shank of the screw tofthe size, 1 or nearly to the sizeof; the stem, leaving ita close fit to the orifice fmade by; thestem of? the screw. y y Q Figure 1 in the anexeddrawing is ps resentation of my 1. improvedwscrew; It (is 1 made of a wire of' the diameter of the threaded part of the screw as here shown, the thread included, the original diameter 2 Q1 of the wire for the shank being indicated by the dotted lines a, and bu I turnflotf or reduce this part of qthetwire, making thelfl shank e, equal-in. diameter withthat. ofthe stem 0, or nearly so. i Itrisevident thatthisgo screw may be driven quitedown to the head d, without any objectionable frictiongmd" that little or no, obstructionlto the sinking..., of thehead into the woodwillbe ofieredfbyQ reason of the crowdingof the shank of thei screw in its orifice, byaneansyofwhich the; 1 screw itself is unharmed by thexprocess of; driving and its hold on the jfibersoftheh 1 wood isunimpaired. j 1 I It is obvious that this improvementlis ap g 7: plicable to all woodscrews, withoutregardfi 11 to their size, to the character xofthefthreadfi or the point of the screw. f a

Having thus described my invention, whatgy 1 I claim as new,-and desireto securej by Let- 81 ters Patent, is: of i i i 1 j The construction of woodlscrews,havinga I shank; or. that portion of the wire lying between the thread, 1 and =fthe head"of them 3} screw, reducedinits diameter, so that with- 8: out any enlargement of the, orifice beyond 1 1 that made by the stem, :fthe screw may be i I driven home withoutincrease of friction at: y the shank, and withoutinjury ;to the screw or to the holdthereof uponfthe fibers ofthe 9( wood, as herein described. 1 1

y Witnesses: l i I 1 WM. B KER,

CHARLES Barnum, 

